U.S. patent application number 11/900806 was filed with the patent office on 2008-11-13 for thermosensitive recording material.
Invention is credited to Toshiaki Ikeda, Takeshi Kajikawa, Masafumi Kumoda, Yoshiaki Matsunaga, Shinji Takano.
Application Number | 20080280757 11/900806 |
Document ID | / |
Family ID | 38814358 |
Filed Date | 2008-11-13 |
United States Patent
Application |
20080280757 |
Kind Code |
A1 |
Matsunaga; Yoshiaki ; et
al. |
November 13, 2008 |
Thermosensitive recording material
Abstract
Provided is a thermosensitive recording material that comprises
a support, a thermosensitive coloring layer on the support, and a
protective layer on the thermosensitive coloring layer, wherein the
thermosensitive coloring layer comprises a leuco dye and a color
developer, and the protective layer comprises a diacetone-modified
polyvinyl alcohol resin and a (meth)acrylic resin.
Inventors: |
Matsunaga; Yoshiaki;
(Numazu-shi, JP) ; Takano; Shinji; (Numazu-shi,
JP) ; Kajikawa; Takeshi; (Sunto-gun, JP) ;
Ikeda; Toshiaki; (Sunto-gun, JP) ; Kumoda;
Masafumi; (Numazu-shi, JP) |
Correspondence
Address: |
COOPER & DUNHAM, LLP
1185 AVENUE OF THE AMERICAS
NEW YORK
NY
10036
US
|
Family ID: |
38814358 |
Appl. No.: |
11/900806 |
Filed: |
September 12, 2007 |
Current U.S.
Class: |
503/226 |
Current CPC
Class: |
B41M 2205/04 20130101;
B41M 5/44 20130101; B41M 2205/40 20130101 |
Class at
Publication: |
503/226 |
International
Class: |
B41M 5/323 20060101
B41M005/323 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 15, 2006 |
JP |
2006-251292 |
Claims
1. A thermosensitive recording material, comprising: a support, a
thermosensitive coloring layer on the support, and a protective
layer on the thermosensitive coloring layer, wherein the
thermosensitive coloring layer comprises a leuco dye and a color
developer, and the protective layer comprises a diacetone-modified
polyvinyl alcohol resin and a (meth)acrylic resin.
2. The thermosensitive recording material according to claim 1,
wherein the (meth)acrylic resin is a homopolymer of one of
(meth)acrylic acid and (meth)acrylates, or a copolymer of at least
one of (meth)acrylic acid and (meth)acrylates as well as a monomer
copolymerizable therewith.
3. The thermosensitive recording material according to claim 1,
wherein the (meth)acrylic resin is a styrene-acrylic acid
copolymer.
4. The thermosensitive recording material according to claim 1,
wherein the amount of the (meth)acrylic resin in the protective
layer is 1 part by mass to 50 parts by mass based on 100 parts by
mass of the diacetone-modified polyvinyl alcohol resin.
5. The thermosensitive recording material according to claim 1,
wherein the acid value of the (meth)acrylic resin is no less than
100 mgKOH/g.
6. The thermosensitive recording material according to claim 1,
wherein the protective layer comprises a hydrazide compound, and
the hydrazide compound is adipic dihydrazide.
7. The thermosensitive recording material according to claim 1,
wherein the thermosensitive recording material is a thermosensitive
recording label that comprises a adhesive layer and a release paper
on the surface of the adhesive layer, on the side of the support
opposite to the thermosensitive coloring layer.
8. The thermosensitive recording material according to claim 1,
wherein the thermosensitive recording material is a thermosensitive
recording label that comprises a thermosensitive adhesive layer
that becomes tacky upon heating, on the side of the support
opposite to the thermosensitive coloring layer.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to thermosensitive recording
materials that are favorably utilized in various fields such as of
computer outputs, calculator printers, medical meter recorders,
low-speed or high-speed facsimiles, ticket vendors and handy
terminals.
[0003] 2. Description of the Related Art
[0004] A number of proposals have been made heretofore for
thermosensitive recording materials that have a thermosensitive
coloring layer containing at least a leuco dye and a color
developer on a support and make use of a coloring reaction between
the leuco dye and the color developer. The thermosensitive
recording materials have such benefits as (i) complicated
procedures like development and fixing are unnecessary, and
recording can be carried out by use of relatively simple devices in
a short period, (ii) noise is low, and (iii) cost is inexpensive,
therefore, have been widely used for copies of books or
literatures, and for recording materials of computers, facsimiles,
ticket vendors, label printers, recorders, handy terminals, or the
like.
[0005] The thermosensitive recording materials have been desired
for quick color development into high concentration as well as high
toughness of colored images and background. In recent years, the
thermosensitive recording materials have been frequently used for
labels etc. that are importantly required for the reliability of
recorded images, in particular, those having high storage stability
for plasticizers and fats-oils are demanded that are included into
organic polymer materials of packages.
[0006] Thermosensitive recording materials have hence been proposed
that are provided with a protective layer on the thermosensitive
coloring layer. The binder resins in the protective layer are
exemplified by polyvinyl alcohol, modified polyvinyl alcohol, or
combinations thereof and water-proof agents. For example, a
combination of a diacetone-modified polyvinyl alcohol and a
hydrazine compound is proposed (see Japanese Patent Application
Laid-Open (JP-A) No. 08-151412). However, when the proposed
material is employed in the protective layer, there arises such a
problem that the coating liquid for the protective layer increases
its viscosity with time since a water-proof reaction is promoted
under the coated condition.
[0007] A thermosensitive recording material is also proposed in
which a diacetone-modified polyvinyl alcohol is employed as a
binder resin of the protective layer and a hydrazine compound is
included into the thermosensitive coloring layer (see JP-A No.
11-314457). However, this proposal suffers from insufficient water
resistance of the protective layer, viscosity rise of the coating
liquid for thermosensitive coloring layer, and/or coloring
inhibition at the thermosensitive coloring layer due to the
hydrazine compound.
[0008] A thermosensitive recording material is also proposed in
which a polyvinyl alcohol copolymer containing diacetone acrylamide
as its monomer, a water-soluble hydrazine compound, and a
water-soluble amine are used (see JP-A No. 10-87936). However, when
the proposed material is employed in the protective layer, there
arise such problems as the background develops a color due to an
adverse effect of the water-soluble amine on the thermosensitive
coloring layer, pH control is difficult, and viscosity rise of the
liquid may be promoted depending on the amount of the water-soluble
amine.
[0009] In order to improve these problems, JP-A No. 2002-283717
discloses a thermosensitive recording material in which a polyvinyl
alcohol having a reactive carbonyl group, a hydrazide compound, and
a basic filler are combined. This proposal may improve the problem
of viscosity rise.
[0010] However, the thermosensitive recording material, which
employs the polyvinyl alcohol having a reactive carbonyl group and
the hydrazide compound as described in JP-A No. 2002-283717,
suffers from such a problem that images printed with aqueous
flexographic ink are easily removed away by an external force upon
contacting the images with water for a long period; and this
problem is currently demanded to be solved.
BRIEF SUMMARY OF THE INVENTION
[0011] The present invention has been made in view of the current
state described above; it is an object of the present invention to
solve the problems in the art and to attain the purpose below. That
is, the present invention aims to provide a highly-sensitive
thermosensitive recording material that imparts excellent water
resistance, superior transportability under high temperature and
high humidity conditions, and appropriate sticking property under
low temperature and low humidity conditions to images of aqueous
flexographic ink printed on its surface.
[0012] The present inventors have investigated vigorously to solve
the problems described above, consequently have found that the
images of aqueous flexographic ink printed on the surface of
thermosensitive recording material can be effectively prevented
from their removal even upon contacting with water and the printed
images are improved in terms of their water resistance, provided
that the thermosensitive recording material comprises a
thermosensitive coloring layer on a support and a protective layer
on the thermosensitive coloring layer, and the thermosensitive
coloring layer comprises a leuco dye and a color developer, and the
protective layer comprises a diacetone-modified polyvinyl alcohol
resin and a (meth)acrylic resin.
[0013] The present invention has been made on the basis of the
founding described above; the problems described above are solved
by the invention as follows:
<1> A thermosensitive recording material, comprising a
support, a thermosensitive coloring layer on the support, and a
protective layer on the thermosensitive coloring layer, wherein the
thermosensitive coloring layer comprises a leuco dye and a color
developer, and the protective layer comprises a diacetone-modified
polyvinyl alcohol resin and a (meth)acrylic resin. <2> The
thermosensitive recording material according to <1>, wherein
the (meth)acrylic resin is a homopolymer of one of (meth)acrylic
acid and (meth)acrylates, or a copolymer of at least one of
(meth)acrylic acid and (meth)acrylates as well as a monomer
copolymerizable therewith. <3> The thermosensitive recording
material according to <1> or <2>, wherein the
(meth)acrylic resin is a styrene-acrylic acid copolymer. <4>
The thermosensitive recording material according to any one of
<1> to <3>, wherein the amount of the (meth)acrylic
resin in the protective layer is 1 part by mass to 50 parts by mass
based on 100 parts by mass of the diacetone-modified polyvinyl
alcohol resin. <5> The thermosensitive recording material
according to any one of <1> to <4>, wherein the acid
value of the (meth)acrylic resin is no less than 100 mgKOH/g.
<6> The thermosensitive recording material according to any
one of <1> to <5>, wherein the protective layer
comprises a hydrazide compound, and the hydrazide compound is
adipic dihydrazide. <7> The thermosensitive recording
material according to any one of <1> to <6>, wherein
the thermosensitive recording material is a thermosensitive
recording label that comprises a adhesive layer and a release paper
on the surface of the adhesive layer, on the side of the support
opposite to the thermosensitive coloring layer. <8> The
thermosensitive recording material according to any one of
<1> to <6>, wherein the thermosensitive recording
material is a thermosensitive recording label that comprises a
thermosensitive adhesive layer that becomes tacky upon heating, on
the side of the support opposite to the thermosensitive coloring
layer.
[0014] The inventive thermosensitive recording material comprises a
support, a thermosensitive coloring layer on the support, and a
protective layer on the thermosensitive coloring layer, wherein the
thermosensitive coloring layer comprises a leuco dye and a color
developer, and the protective layer comprises a diacetone-modified
polyvinyl alcohol resin and a (meth)acrylic resin. The images,
printed by the aqueous flexographic ink on the surface of the
inventive thermosensitive recording material, may have a higher
bonding strength at the boundary between the protective layer and
the aqueous flexographic ink since a bond generates between the
carboxyl group of the acrylic resin in the protective layer and the
bonder resin in the aqueous flexographic ink. As a result, the
images printed by the aqueous flexographic ink may exhibit
excellent water resistance, superior transportability under high
temperature and high humidity conditions, and appropriate sticking
property under low temperature and low humidity conditions.
[0015] The flexographic ink is typically classified into alcohol
type and aqueous type depending on the solvent therein. The
flexographic ink of alcohol type is typically produced using
alcohol solvents of one having a lower-boiling point such as
ethanol and one having a higher-boiling point such as glycol. On
the other hand, the type of the aqueous flexographic ink contains
water and optional very small amount of alcohol, and contains
substantially no solvents, thus is appropriate for resource saving
and environmental sanitation, and is widely used.
[0016] In accordance with the present invention, high sensitive
thermosensitive recording materials can be produced that solve the
problems in the art, that is, the images printed on the surface by
the aqueous flexographic ink may exhibit excellent water
resistance, superior transportability under high temperature and
high humidity conditions, and appropriate sticking property under
low temperature and low humidity conditions.
DETAILED DESCRIPTION OF THE INVENTION
[0017] The inventive thermosensitive recording material comprises a
support, a thermosensitive coloring layer on the support, a
protective layer on the thermosensitive coloring layer, and
optional other layers such as a back layer and an intermediate
layer as required.
Protective Layer
[0018] The protective layer contains a diacetone-modified polyvinyl
alcohol resin, a (meth)acrylic resin, a crosslinking agent, and
optional other ingredients.
Diacetone-Modified Polyvinyl Alcohol Resin
[0019] The diacetone-modified polyvinyl alcohol resin, which being
formed of a polyvinyl alcohol of which the hydroxyl group is
modified by diacetone, may be properly synthesized or commercially
available.
[0020] In cases of synthesis, the diacetone-modified polyvinyl
alcohol resin may be prepared through conventional processes, for
example, by way of saponifying a copolymer obtained from
copolymerizing a vinyl monomer having a diacetone group and a fatty
acid vinyl ester.
[0021] The vinyl monomer having the diacetone group is exemplified
by diacetone acrylamide and diacetone methacrylamide.
[0022] The fatty acid vinyl ester is exemplified by vinyl formate,
vinyl acetate, and vinyl propionate. Among these, vinyl acetate is
preferable in particular.
[0023] The diacetone-modified polyvinyl alcohol resin may be one
copolymerized with other copolymerizable vinyl monomers. Examples
of the copolymerizable vinyl monomers include acrylic acid esters,
butadiene, ethylene, propylene, acrylic acid, methacrylic acid,
maleic acid, maleic anhydride and itaconic acid.
[0024] The amount of the reactive carbonyl group in the
diacetone-modified polyvinyl alcohol resin is preferably 0.5 to 20%
by mole in the polymer, more preferably 2 to 10% by mole. When the
amount is below 0.5% by mole, the water resistance may be
practically insufficient, and even when the amount is above 20% by
mole, the water resistance may not be enhanced proportionally and
the cost tends to be expensive.
[0025] The polymerization degree of the diacetone-modified
polyvinyl alcohol resin may be properly selected depending on the
application; preferably, the polymerization degree is 300 to 3,000,
more preferably 500 to 2,000.
(Meth)acrylic Resin
[0026] The (meth)acrylic resin may be properly selected from
conventional ones, and may be appropriately synthesized or
commercially available.
[0027] In cases of synthesis, it is preferred that the
(meth)acrylic resin is a homopolymer of one of (meth)acrylic acid
and (meth)acrylates, or a copolymer of at least one of
(meth)acrylic acid and (meth)acrylates as well as a monomer
copolymerizable therewith.
[0028] The (meth)acrylate may be properly selected depending on the
application; for example, the (meth)acrylate is preferably one of
monomers or oligomers employed for UV-ray curable resins or
electron beam curable resins. Among these, the (meth)acrylate is
one having a flexible structure, more preferably an aliphatic
compound. In cases of aromatic compounds, the (meth)acrylate
preferably has a chain structure. Monofunctional or difunctional
monomers are more preferable than polyfunctional polymers of
trivalence or more.
[0029] Examples of the (meth)acrylate include alkyl(meth)acrylates
having an alkyl group, amino(meth)acrylates having an alkyl group,
glycol di(meth)acrylate, allyl(meth)acrylate, trimethylolpropane
tri(meth)acrylate, glycidyl(meth)acrylate, acrylamide, diacetone
acrylamide, (meth)acrylonitrile, benzyl(meth)acrylate, and
dimethylaminoethly (meth)acrylate methylchloride salt. These may be
used alone or in combination of two or more.
[0030] The alkyl(meth)acrylate having an alkyl group may be
properly selected depending on the application, its carbon number
is preferably 1 to 18, more preferably 3 to 15; specific examples
thereof include methyl(meth)acrylate, ethyl(meth)acrylate,
n-butyl(meth)acrylate, i-butyl(meth)acrylate,
cyclohexyl(meth)acrylate, 2-ethylhexyl(meth)acrylate,
lauryl(meth)acrylate, and stearyl(meth)acrylate.
[0031] Less carbon number of the alkyl group may lead to
insufficient flexibility of the (meth)acrylic resin, and larger
carbon number thereof may also lead to insufficient flexibility due
to regular arrangement of methylene side chains.
[0032] The amino(meth)acrylate having an alkyl group may be
properly selected depending on the application, the carbon number
is preferably 1 to 5; examples thereof include
dimethylaminoethyl(meth)acrylate and
diethylaminoethyl(meth)acrylate.
[0033] The glycol di(meth)acrylate may be properly selected
depending on the application; examples thereof include
ethyleneglycol di(meth)acrylate and butyleneglycol
di(meth)acrylate.
[0034] Examples of the copolymerizable monomer include vinylarenes
such as styrene, .alpha.-methylstyrene, monochlorostyrene and
dichlorostyrene; vinylcyans such as acrylonitrile and
methacrylonitrile; halogenated vinyls such as vinyl chloride, vinyl
bromide and chloroprene; vinyl acetate; alkenes such as ethylene,
propylene, butylene, butadiene and isobutylene; halogenated
alkenes; and polyfunctional monomers such as allylmethacrylate,
diallylphthalate, triallylcyanurate, monoethyleneglycol
dimethacrylate, tetraethyleneglycol dimethacrylate, divinylbenzene,
and glycidyl methacrylate.
[0035] These (meth)acrylic resins may be used alone or in
combination of two or more. Among these, preferable are acrylic
resins having a copolymer component of methylacrylate,
butylacrylate or 2-etylhexylacrylate, or having a copolymer
component thereof as well as a copolymer component of
methacrylates, styrene, acrylonitrile, or vinyl acetate; in
particular, styrene-acrylic acid copolymers are preferable in view
of binding ability with resins in aqueous flexographic ink.
[0036] The acrylic resins of water-soluble type and emulsion type
may equivalently provide printed images with water resistance;
preferably, water-soluble type is employed since emulsion type may
provide contradictory effects to decrease barrier property such as
plasticizer resistance and oil resistance.
[0037] The amount of the (meth)acrylic resin in the protective
layer is preferably 1 to 50 parts by mass based on 100 parts by
mass of the diacetone-modified polyvinyl alcohol resin, more
preferably 5 to 30 parts by mass. When the amount is less than 1
part by mass, the effect on water resistance may be insignificant
for the images printed by aqueous flexographic ink, and when the
amount is more than 50 parts by mass, the sticking property may be
poor under low temperature and low humidity conditions.
[0038] The acid value of the (meth)acrylic resin is preferably no
less than 100 mgKOH/g, more preferably 150 to 250 mgKOH/g. When the
acid value is less than 100 mgKOH/g, the effect on water resistance
may be insufficient for the images printed by aqueous flexographic
ink. The acid value of the (meth)acrylic resin may be measured in
accordance with the procedures defined in JIS K0070, for
example.
[0039] The mass average molecular mass of the (meth)acrylic resin
may be properly selected depending on the application; preferably,
the mass average molecular mass is 1,000 to 300,000.
Crosslinking Agent
[0040] The crosslinking agent may be properly selected depending on
the application; preferably, the crosslinking agent is a hydrazide
compound.
[0041] The hydrazide compound may be properly selected depending on
the application as long as having a hydrazide group; examples
thereof include hydrazine, carbohydrazide, oxalic dihydrazide,
formic hydrazide, acetic hydrazide, malonic dihydrazide, succinic
dihydrazide, adipic dihydrazide, azelaic dihydrazide, sebacic
dihydrazide, dodecanedioic acid dihydrazide, maleic dihydrazine,
fumaric dihydrazide, itaconic dihydrazide, benzoic hydrazide,
glutaric dihydrazide, diglycol acid dihydrazide, tartaric
dihydrazide, malic dihydrazide, isophthalic hydrazide, terephthalic
dihydrazide 2,7-naphthoic dihydrazide and polyacrylic acid
hydrazide. These may be used alone or in combination of two or
more. Among these, adipic dihydrazide is particularly preferable
from the viewpoint of water resistance and safety.
[0042] The amount of the crosslinking agent depends on modification
degree, species etc. of the functional group in the crosslinking
agent; preferably, the amount of the crosslinking agent is 0.1 to
20 parts by mass based on 100 parts by mass of the
diacetone-modified polyvinyl alcohol resin, more preferably 1 to 10
parts by mass.
[0043] The inventive crosslinking agent may be combined with
conventional crosslinking agents such as glyoxal, melamine,
aziridine compounds, polyamide epichlorohydrin resins, ammonium
zirconium carbonate and ethylene diamine, within an appropriate
range.
[0044] The protective layer may contain a filler as required.
Examples of the filler include inorganic fine powders such as of
aluminum hydroxide, calcium carbonate, silica, zinc oxide, titanium
oxide, zinc hydroxide, barium sulfate, clay, talc, surface-treated
calcium and surface-treated silica; organic fine powders such as of
urea-formalin resins, styrene-methacrylic acid copolymers and
polystyrene resins. Among these, aluminum hydroxide and calcium
carbonate are particularly preferable from the view point of
excellent wear resistance as regards thermal heads on printing for
a long period.
[0045] The protective layer may be formed by processes properly
selected depending on the purpose; preferably, the protective layer
is formed by way of coating a liquid for protective layer on the
thermosensitive coloring layer.
[0046] The coating process may be properly selected depending on
the application; examples of the coating process include spin
coating processes, dip coating processes, kneader coating
processes, curtain coating processes and blade coating processes.
Among these, spin coating processes and dip coating processes are
particularly preferable in view of coating efficiency.
[0047] The coated layer may be dried after the coating process; the
drying temperature may be properly selected depending on the
application, preferably, the temperature is 100.degree. C. to
250.degree. C.
[0048] The coated amount of the protective layer after drying may
be properly selected depending on the application; preferably, the
coated amount after drying is 0.5 to 5.0 g/m.sup.2, more preferably
1.5 to 3.5 g/m.sup.2. When the coated amount after drying is less
than 0.5 g/m.sup.2, the function as the protective layer may be
insufficient such that printed images may be discolored by external
action of oils, plasticizers, water, chemicals etc., and even when
the amount is more than 5.0 g/m.sup.2, the function as the
protective layer may not be enhanced proportionally, rather the
coloring sensitivity may be deteriorated.
Thermosensitive Coloring Layer
[0049] The thermosensitive coloring layer contains at least a leuco
dye, a color developer, and a binder resin, and also other
ingredients as required.
Leuco Dye
[0050] The leuco dye may be properly selected from those
conventionally used for thermosensitive recording materials
depending on the purpose; preferable examples are leuco compounds
such as triphenylmethanes, fluorans, phenothiazines, auramines,
spiropyranes and indolinophthalides.
[0051] Specific examples of the leuco dye include [0052]
2-anilino-3-methyl-6-dibutylaminofluoran, [0053]
3,3-bis(p-dimethylaminophenyl)phthalide, [0054]
3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (referred
to also as Crystal Violet lactone), [0055]
3,3-bis(p-dimethylaminophenyl)-6-diethylaminophthalide, [0056]
3,3-bis(p-dimethylaminophenyl)-6-chlorophthalide, [0057]
3,3-bis(p-dibutylaminophenyl)phthalide, [0058]
3-cyclohexylamino-6-chlorofluoran, [0059]
3-dimethylamino-5,7-dimethylfluoran, [0060]
3-diethylamino-7-chlorofluoran, 3-diethylamino-7-methylfluoran,
[0061] 3-diethylamino-7,8-benzofluoran, [0062]
3-diethylamino-6-methyl-7-chlorofluoran, [0063]
3-(N-p-tolyl-N-ethylamino)-6-methyl-7-anilinofluoran, [0064]
2-[N-(3'-trifluoromethylphenyl)amino]-6-diethylaminofluoran, [0065]
2-[3,6-bis(diethylamino)-9-(o-chloroanilino)xanthylbenzoic acid
lactam], [0066]
3-diethylamino-6-methyl-7-(m-trichloromethylanilino) fluoran,
[0067] 3-diethylamino-7-(o-chloroanilino)fluoran, [0068]
3-pyrrolidino-6-methyl-7-anilinofluoran, [0069]
3-di-n-butylamino-7-o-chloroanilinofluoran, [0070]
3-N-methyl-N,n-amylamino-6-methyl-7-anilinofluoran, [0071]
3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluoran, [0072]
3-diethylamino-6-methyl-7-anilinofluoran, [0073]
3-(N,N-diethylamino)-5-methyl-7-(N,N-dibenzylamino)fluoran, benzoyl
leuco methylene blue, [0074]
6'-chloro-8'-methoxy-benzoindolino-spiropyran, [0075]
6'-bromo-3'-methoxy-benzoindolino-spiropyran, [0076]
3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)phtha-
lide, [0077]
3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-nitrophenyl)phthal-
ide, [0078]
3-(2'-hydroxy-4'-diethylaminophenyl)-3-(2'-methoxy-5'-methylphenyl)phthal-
ide, [0079]
3-(2'-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chloro-5'-methylph-
enyl)phthalide, [0080]
3-(N-ethyl-N-tetrahydrofurfuryl)amino-6-methyl-7-anilinofluoran,
[0081] 3-N-ethyl-N-(2-ethoxypropyl)amino-6-methyl-7-anilinofluoran,
[0082] 3-N-methyl-N-isobutyl-6-methyl-7-anilinofluoran, [0083]
3-morpholino-7-(N-propyl-trifluoromethylanilino)fluoran, [0084]
3-pyrrolidino-7-trifluoromethylanilinofluoran, [0085]
3-diethylamino-5-chloro-7-(N-benzyl-trifluoromethylanilino)fluoran,
[0086] 3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluoran,
[0087] 3-diethylamino-5-chloro-7-(.alpha.-phenylethylamino)fluoran,
[0088] 3-(N-ethyl-p-toluidino)-7-(.alpha.-phenylethylamino)fluoran,
[0089] 3-diethylamino-7-(o-methoxycarbonylphenylamino)fluoran,
[0090] 3-diethylamino-5-methyl-7-(.alpha.-phenylethylamino)fluoran,
[0091] 3-diethylamino-7-piperidinofluoran, [0092]
2-chloro-3-(N-methyltoluidino)-7-(p-n-butylanilino)fluoran, [0093]
3-di-n-butylamino-6-methyl-7-anilinofluoran, [0094]
3,6-bis(dimethylamino)fluorenespiro(9,3')-6'-dimethylaminophthalide,
[0095]
3-(N-benzyl-N-cyclohexylamino)-5,6-benzo-7-.alpha.-naphthylamino-4-
'-bromofluoran, [0096] 3-diethylamino-6-chloro-7-anilinofluoran,
[0097] 3-diethylamino-6-methyl-7-mesitidino-4',5'-benzofluoran,
[0098] 3-N-methyl-N-isopropyl-6-methyl-7-anilinofluoran, [0099]
3-N-ethyl-N-isoamyl-6-methyl-7-anilinofluoran, [0100]
3-diethylamino-6-methyl-7-(2',4'-dimethylanilino)fluoran, [0101]
3-morpholino-7-(N-propyl-trifluoromethylanilino)fluoran, [0102]
3-pyrrolidino-7-trifluoromethylanilinofluoran, [0103]
3-diethylamino-5-chloro-7-(N-benzyl-trifluoromethylanilino)fluoran,
[0104] 3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluoran,
[0105] 3-diethylamino-5-chloro-(.alpha.-phenylethylamino)fluoran,
[0106] 3-(N-ethyl-p-toluidino)-7-.alpha.-phenylethylamino)fluoran,
[0107] 3-diethylamino-7-(o-methoxycarbonylphenylamino)fluoran,
[0108] 3-diethylamino-5-methyl-7-(.alpha.-phenylethylamino)fluoran,
[0109] 3-diethylamino-7-pyperidinofluoran, [0110]
2-chloro-3-(N-methyltoluidino)-7-(p-N-butylanilino)fluoran, [0111]
3,6-bis(dimethylamino)fluorenspiro(9,3')-6'-dimethylaminophthalide,
[0112]
3-(N-benzyl-N-cyclohexylamino)-5,6-benzo-7-.alpha.-naphthylamino-4-
'-bromofluoran, [0113] 3-diethylamino-6-chloro-7-anilinofluoran,
[0114] 3-N-ethyl-N-(2-ethoxypropyl)amino-6-methyl-7-anilinofluoran,
[0115]
3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofluoran,
[0116] 3-diethylamino-6-methyl-7-mesitidino-4',5'-benzofluoran,
[0117]
3-(p-dimethylaminophenyl)-3-[1,1-bis(p-dimethylaminophenyl)-ethylene-2-yl-
]phthalide, [0118]
3-(p-dimethylaminophenyl)-3-[1,1-bis(p-dimethylaminophenyl)-ethylene-2-yl-
]-6-dimethylaminophthalide, [0119]
3-(p-dimethylaminophenyl)-3-(1-p-dimethylaminophenyl-1-phenylethylene-2-y-
l)phthalide, [0120]
3-(p-dimethylaminophenyl)-3-(1-p-dimethylaminophenyl-1-p-chlorophenylethy-
lene-2-yl)-6-dimethylaminophthalide, [0121]
3-(4'-dimethylamino-2'-methoxy)-3-(1''-p-dimethylaminophenyl-1''-p-chloro-
phenyl-1'', 3''-butadiene-4''-yl)benzophthalide, [0122]
3-(4'-dimethylamino-2'-benzyloxy)-3-(1''-p-dimethylaminophenyl-1''-phenyl-
-1'',3''-butadiene-4''-yl)benzophthalide, [0123]
3-dimethylamino-6-dimethylamino-fluorene-9-spiro-3'-(6'-dimethylamino)pht-
halide, [0124]
3,3-bis[2-(p-dimethylaminophenyl)-2-(p-methoxyphenyl)ethenyl]-4,5,6,7-tet-
rachlorophthalide, [0125]
3-bis[1,1-bis(4-pyrrolidinophenyl)ethylene-2-yl]-5,6-dichloro-4,7-dibromo-
phthalide, [0126]
bis(p-dimethylaminostyryl)-1-naphthalenesulfonylmethane, [0127]
bis(p-dimethylaminostyryl)-1-p-tolylsulfonylmethane. These may be
used alone or in combination of two or more.
Color Developer
[0128] The color developer may be various electron-accepting
compounds or oxidants that colors the leuco dyes upon contacting
therewith.
[0129] The color developer may be properly selected from
conventional ones; specific examples thereof include
4,4'-isopropylidene bisphenol, 4,4'-isopropylidene
bis(o-methylphenol), 4,4'-sec-butylidene bisphenol,
4,4'-isopropylidenebis(2-ter-butylphenol), p-nitrobenzoic acid
zinc,
1,3,5-tris(4-ter-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric
acid, 2,2-(3,4'-dihydroxydiphenyl)propane,
bis(4-hydroxy-3-methylphenyl)sulfide,
4-[.beta.-(p-methoxyphenoxy)ethoxy]salicylic acid,
1,7-bis(4-hydroxyphenylthio)-3,5-dioxaheptane,
1,5-bis(4-hydroxyphenylthio)-5-oxapentane, monobenzylphthalate mono
calcium salt, 4,4'-cyclohexylidenediphenol, 4,4'-isopropylidene
bis(2-chlorophenol), 2,2'-methylenebis(4-methyl-6-ter-butylphenol),
4,4'-butylidenebis(6-ter-butyl-2-methyl)phenol,
1,1,3-tris(2-methyl-4-hydroxy-5-ter-butylphenyl)butane,
1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane,
4,4'-thiobis(6-ter-butyl-2-methyl)phenol, 4,4'-diphenolsulfone,
4-isopropoxy-4'-hydroxydiphenylsulfone-(4-hydroxy-4'-isopropoxydiphenylsu-
lfone), 4-benzyloxy-4'-hydroxydiphenylsulfone,
4,4'-diphenolsulfoxide, p-hydroxyisopropylbenzoate,
p-hydroxybenzylbenzoate, benzyl protocatechuate, stearyl gallicate,
lauryl gallicate, octyl gallicate,
1,3-bis(4-hydroxyphenylthio)propane, N,N'-diphenylthiourea,
N,N'-di(m-chlorophenyl)thiourea, salicylanilide,
bis(4-hydroxyphenyl)methylacetate,
bis(4-hydroxyphenyl)benzylacetate, 1,3-bis(4-hydroxycumyl)benzene,
1,4-bis(4-hydroxycumyl)benzene, 2,4'-duphenolsulfone,
2,2'-diallyl-4,4'-diphenolsulfone,
3,4-dihydroxyphenyl-4'-methyldiphenylsulfone, 1-acetyloxy-2-zinc
naphthoate, 2-acetyloxy-1-zinc naphthoate, 2-acetyloxy-3-zinc
naphthoate,
.alpha.,.alpha.-bis(4-hydroxyphenyl)-.alpha.-methyltoluene,
antipyrine complex of zinc thiocyanate, tetrabromobisphenol A,
tetrabromobisphenol S, 4,4'-thiobis(2-methylphenol) and
4,4'-thiobis(2-chlorophenol). These may be used alone or in
combination of two or more.
[0130] The amount of the color developer is preferably 1 to 20
parts by mass based on 1 part of the leuco dye, more preferably 2
to 10 parts by mass.
Binder Resin
[0131] The binder resin may be properly selected from conventional
ones depending on the application; examples thereof include
polyvinyl alcohol; starch and its derivatives; cellulose
derivatives such as methoxy cellulose, hydroxyethyl cellulose,
carboxymethyl cellulose, methyl cellulose and ethyl cellulose;
water-soluble polymers such as sodium polyacrylate, polyvinyl
pyrrolidone, acrylamide-acrylate copolymers,
acrylamide-acrylate-methacrylic acid terpolymers, alkali salts of
styrene-maleic anhydride copolymers, alkali salts of
isobutylene-maleic anhydride copolymers, polyacrylamide, sodium
alginate, gelatin and casein; emulsions such as of polyvinyl
acetate, polyurethane, polyacrylic acid, polyacrylate,
polymethacrylate, polybutylmethacrylate, vinyl chloride-vinyl
acetate copolymers and ethylene-vinyl acetate copolymers; and
latexes such as styrene-butadiene copolymers and
styrene-butadiene-acrylate terpolymers. These may be used alone or
in combination of two or more.
[0132] The thermosensitive coloring layer may contain various
heat-meltable substances as sensitivity enhancing agents. Examples
of the heat-meltable substances include fatty acids such as stearic
acid and behenic acid; fatty acid amides such as stearic acid amide
and palmitic acid amide; metal salts of fatty acid such as zinc
stearate, aluminum stearate, calcium stearate, zinc palmitate and
zinc behenate; p-benzylbiphenyl, terphenyl, triphenylmethane,
p-benzyloxybenzylbenzoate, .beta.-benzyloxynaphthalene,
.beta.-phenylnaphthoate, 1-hydroxy-2-phenylnaphthoate,
1-hydroxy-2-methylnaphthoate, diphenylcarbonate, dibenzyl
terephthalate, dimethyl terephthalate, 1,4-dimethoxynaphthalene,
1,4-diethoxynaphthalene, 1,4-dibenzyloxynaphthalene,
1,2-bis(phenoxy)ethane, 1,2-bis(3-methylphenoxy)ethane,
1,2-bis(4-methylphenoxy)ethane, 1,4-bis(phenoxy)butane,
1,4-bis(phenoxy)-2-butene, 1,2-bis(4-methoxyphenylthio)ethane,
dibenzoylmethane, 1,4-bis(phenylthio)butane,
1,4-bis(phenylthio)-2-butene, 1,2-bis(4-methoxyphenylthio)ethane,
1,3-bis(2-vinyloxyethoxy)benzene, 1,4-bis(2-vinyloxyethoxy)benzene,
p-(2-vinyloxyethoxy)biphenyl, p-aryloxybiphenyl,
p-propargyloxybiphenyl, dibenzoyloxymethane,
1,3-dibenzoyloxypropane, dibenzyl disulfide, 1,1-diphenylethanol,
1,1-diphenylpropanol, p-(benzyloxy)benzylalcohol,
1,3-diphenoxy-2-propanol,
N-octadecylcarbamoyl-p-methoxycarbonylbenzene,
N-octadecylcarbamoylbenzene, dibenzyl oxalate and
1,5-bis(p-methoxyphenoxy)-3-oxapentane. These may be used alone or
in combination of two or more.
[0133] The thermosensitive coloring layer may contain optionally
various auxiliary additives such as surfactants, lubricants and
fillers. Examples of the lubricant include higher fatty acids and
metal salts thereof, higher fatty acid amides, higher fatty acid
esters, animal waxes, vegetable waxes, mineral waxes and petroleum
waxes.
[0134] Examples of the filler include inorganic fine powders such
as calcium carbonate, silica, zinc oxide, titanium oxide, aluminum
hydroxide, zinc hydroxide, barium sulfate, clay, kaolin, talc,
surface-treated calcium and surface-treated silica; organic fine
powders such as of urea-formalin resins, styrene-methacrylic acid
copolymers, polystyrene resins and vinylidene chloride resins.
[0135] The thermosensitive coloring layer may be properly formed by
conventional processes; for example, the leuco dye and the color
developer are separately milled and dispersed, together with a
binder and/or other ingredients, into a particle diameter of 0.1 to
3 .mu.m using milling apparatuses such as ball mills, attritors and
sand mills, then are mixed together with a filler, a lubricant,
etc. as required under a pre-determined formulation, thereby to
prepare a coating liquid for a thermosensitive coloring layer, then
which is coated on a support to prepare a thermosensitive coloring
layer.
[0136] The coated amount of the thermosensitive coloring layer
after drying depends on the composition and application thereof,
and is not limited specifically; preferably, the coated amount is 1
to 20 g/m.sup.2, more preferably 3 to 10 g/m.sup.2.
Support
[0137] The support may be properly selected with respect to the
shape, configuration, size, material, etc. depending on the
purpose. The shape may be sheet-like, roll-like, plate-like, etc.;
the configuration may be mono-layer or laminate layer; the size may
be appropriately selected depending on the size of thermosensitive
recording materials etc. Examples of the material include plastic
film, synthetic paper film, high quality paper, recycled pulp,
recycled paper, one-side glazed paper, oil resistant paper, coated
paper, art paper, cast-coated paper, light weight coated paper, and
resin-laminated paper.
[0138] More specifically, the support may be paper, film, synthetic
paper, or release coated paper. The paper may be acid paper or
acid-free paper. The release coated paper, which being formed of
acid-free paper and its support, is preferably of lower calcium
content. Such release coated paper of lower calcium content may be
produced by way of reducing the content of old paper in the paper
making process. In addition, talc or clay is used as the internal
additive in combination with a neutral rosin sizing agent when
producing acid-free paper of lower calcium content, although
calcium carbonate is used as the internal additive and alkylketene
dimer or alkenyl succinic acid anhydride is used as a neutral rosin
sizing agent in usual processes.
[0139] The thickness of the support may be properly selected
depending on the application; preferably, the thickness is 30 to
2,000 .mu.m, more preferably 50 to 1,000 .mu.m.
[0140] The inventive thermosensitive recording material may be
constructed to contain the support, the thermosensitive coloring
layer on the support, and the protective layer on the
thermosensitive coloring layer; a back layer may be disposed on the
side of the support opposite to the thermosensitive coloring layer;
and an intermediate layer or a heat-insulating layer may be
disposed between the support and the thermosensitive coloring
layer, between the thermosensitive coloring layer and the
protective layer, and/or the support and the back layer. It is
particularly preferable among these that a heat-insulating layer is
disposed between the support and the thermosensitive coloring
layer. The heat-insulating layer preferably contains hollow resin
particles having an empty rate of 80% or more as a filler. These
layers may be of mono-layer or multi-layer.
[0141] The inventive thermosensitive recording material may exhibit
significantly high contact with thermal heads by treating with
calenders, thus it is particularly preferable to treat the
thermosensitive coloring layer or the protective layer with
calenders. That is, highly fine and precise and thermosensitive
recording material free from background blushing can be obtained by
controlling the surface smoothness of the thermosensitive coloring
layer or the protective layer by means of a pressure of calender
treatment.
Thermosensitive Recording Label
[0142] The thermosensitive recording label in the first embodiment,
which being one of inventive thermosensitive recording material,
contains a adhesive layer on the side of the support opposite to
the thermosensitive coloring layer, a release paper on the surface
of the adhesive layer, and optional other components. The back
layer described above may be also disposed on the same side.
[0143] The material of the adhesive layer may be properly selected
depending on the application; examples of the material include urea
resins, melamine resins, phenol resins, epoxy resins, vinyl acetate
resins, vinyl acetate-acrylate copolymers, ethylene-vinyl acetate
copolymers, acrylic resins, polyvinylether resins, vinyl
chloride-vinyl acetate copolymers, polystyrene resins, polyester
resins, polyurethane resins, polyamide resins, chlorinated
polyolefin resins, polyvinyl butyral resins, acrylate copolymers,
methacrylate copolymers, natural rubbers, cyanoacrylate resins and
silicone resins. These may be used alone or in combination.
[0144] The thermosensitive recording label in the second embodiment
has a thermosensitive adhesive layer that becomes tacky upon
heating and other optional components on the back side of the
support opposite to the thermosensitive recording layer. The back
layer described above may be also disposed on the same side.
[0145] The thermosensitive adhesive layer includes a thermoplastic
resin, a heat-meltable substance, and an optional adhesive
auxiliary agent.
[0146] The thermoplastic resin may afford tackiness and/or adhesive
force. The heat-meltable substance, which being solid at room
temperature thus far from the plasticity, may represent tackiness
through swelling and/or softening a resin upon heating and melting.
The adhesive auxiliary agent may enhance tackiness.
Thermosensitive Magnetic Recording Paper
[0147] The thermosensitive magnetic recording paper, which being
one of thermosensitive recording materials, has a magnetic
recording layer and other optional components on the back side of
the support opposite to the thermosensitive recording layer. The
back layer described above may be also disposed on the same
side.
[0148] The magnetic recording layer may be formed on the support
through coating by use of iron oxide, barium ferrite or the like as
well as vinyl chloride, urethane, nylon resins or the like,
alternatively through vapor-deposition or sputtering with no use of
resins.
[0149] The magnetic recording layer is preferably formed on the
side of the support opposite to the thermosensitive coloring layer,
alternatively may be disposed between the support and the
thermosensitive coloring layer or on a part of the thermosensitive
coloring layer.
[0150] The shape of the thermosensitive recording material may be
properly selected depending on the purpose; preferable shape is
label-like, sheet-like or roll-like.
[0151] The process for recording the thermosensitive recording
material according to the present invention may be carried out,
without limitation, by use of heat pens, thermal heads, laser
heating, etc.
[0152] The thermosensitive recording materials according to the
present invention may be appropriately used in a wide variety of
fields such as POS field like perishable foods, lunch boxes and
daily dishes; copy fields like books and literatures; communication
field like facsimile; ticketing field like ticketing devices,
receipts and acknowledgement; air plane field like package tags;
and may be favorably used under conditions or sites where water
contacts with thermosensitive recording material like within
refrigerators, on display racks in supermarkets, or around water
systems, since images printed by aqueous flexographic ink on the
thermosensitive recording materials are not easily removed away
even after contacting with water for a long period.
EXAMPLES
[0153] The present invention will be explained with reference to
Examples, which are given for no more than illustration of the
invention rather than for limiting its intended scope. All
percentages and parts are by mass unless indicated otherwise.
Example 1
Preparation of Thermosensitive Recording Material
(1) Preparation of Dye Dispersion (A Liquid)
[0154] The composition of the ingredients below was milled and
dispersed till an average particle diameter of 0.5 .mu.m using a
sand mill to prepare A liquid.
TABLE-US-00001 2-anilino-3-methyl-6-dibutylaminofluoran 20 parts
10% aqueous solution of PVA*.sup.1) 20 parts water 60 parts
*.sup.1)PVA: polyvinyl alcohol
(2) Preparation B Liquid
[0155] The composition of the ingredients below was milled and
dispersed till an average particle diameter of 1.5 .mu.m using a
ball mill to prepare B liquid.
TABLE-US-00002 aluminum hydroxide 20 parts
4-hydroxy-4'-isopropoxydiphenylsulfone 20 parts 10% aqueous
solution of PVA 20 parts water 40 parts
(3) Preparation C Liquid
[0156] The composition of the ingredients below was milled and
dispersed till an average particle diameter of 1.5 .mu.m using a
ball mill to prepare C liquid.
TABLE-US-00003 aluminum hydroxide 100 parts 10% aqueous solution of
PVA 20 parts water 40 parts
(4) Preparation of Coating Liquid for Thermosensitive Coloring
Layer
[0157] The composition of the ingredients below was mixed to
prepare a coating liquid for thermosensitive coloring layer.
TABLE-US-00004 A liquid described above 20 parts B liquid described
above 60 parts aqueous solution of resin*.sup.1) 30 parts aqueous
solution of dioctyl sulfosuccinate*.sup.2) 1 part
*.sup.1)diacetone-modified PVA, solid content: 10% *.sup.2)solid
content: 5%
(5) Preparation of Coating Liquid for Protective Layer
[0158] The composition of the ingredients below was mixed to
prepare a coating liquid for protective layer.
TABLE-US-00005 C liquid described above 60 parts aqueous solution
of diacetone-modified PVA*.sup.1) 100 parts aqueous solution of
acrylic resin*.sup.2) 20 parts aqueous solution of adipic
dihydrazide*.sup.3) 10 parts aqueous solution of dioctyl
sulfosuccinate*.sup.4) 1 part *.sup.1)solid content: 10%
*.sup.2)acid value: 600 mgKOH/g, sodium polyacrylate, Jurymer
AC103, solid content: 10%, by Nihon Junyaku Co. *.sup.3)solid
content: 10% *.sup.4)solid content: 5%
(6) Preparation of Thermosensitive Recording Material
[0159] The coating liquid for thermosensitive coloring layer was
coated on a support of high quality paper with a basic weight of 60
g/m.sup.2 in an amount of 0.50 g/m.sup.2 as regards the deposited
dye thereon and dried to form a thermosensitive coloring layer. The
coating liquid for protective layer was then coated on the
thermosensitive coloring layer in an amount of 3.0 g/m.sup.2 as
regards the dried mass thereon to form a protective layer, followed
by treating with a super calender. Consequently, the
thermosensitive recording paper as the thermosensitive recording
material of Example 1 was prepared.
Example 2
Preparation of Thermosensitive Recording Material
[0160] The thermosensitive recording material of Example 2 was
prepared in the same manner as Example 1, except that 20 parts of
an aqueous solution of styrene-acrylic acid copolymer resin (acid
value: 195 mgKOH/g, solid content: 10%, Johncryl 61J, by Johnson
Polymer Co.) was used in place of the aqueous solution of acrylic
resin for the coating liquid for the protective layer of Example
1.
Example 3
Preparation of Thermosensitive Recording Material
[0161] The thermosensitive recording material of Example 3 was
prepared in the same manner as Example 1, except that 2 parts of an
aqueous solution of styrene-acrylic acid copolymer resin (acid
value: 195 mgKOH/g, solid content: 10%, Johncryl 61J, by Johnson
Polymer Co.) was added in place of the aqueous solution of acrylic
resin for the coating liquid for the protective layer of Example
1.
Example 4
Preparation of Thermosensitive Recording Material
[0162] The thermosensitive recording material of Example 4 was
prepared in the same manner as Example 1, except that 0.5 parts of
an aqueous solution of styrene-acrylic acid copolymer resin (acid
value: 195 mgKOH/g, solid content: 10%, Johncryl 61J, by Johnson
Polymer Co.) was used in place of the aqueous solution of acrylic
resin for the coating liquid for the protective layer of Example
1.
Example 5
Preparation of Thermosensitive Recording Material
[0163] The thermosensitive recording material of Example 5 was
prepared in the same manner as Example 1, except that 45 parts of
an aqueous solution of styrene-acrylic acid copolymer resin (acid
value: 195 mgKOH/g, solid content: 10%, Johncryl 61J, by Johnson
Polymer Co.) was used in place of the aqueous solution of acrylic
resin for the coating liquid for the protective layer of Example
1.
Example 6
Preparation of Thermosensitive Recording Material
[0164] The thermosensitive recording material of Example 6 was
prepared in the same manner as Example 1, except that 55 parts of
an aqueous solution of styrene-acrylic acid copolymer resin (acid
value: 195 mgKOH/g, solid content: 10%, Johncryl 61J, by Johnson
Polymer Co.) was used in place of the aqueous solution of acrylic
resin for the coating liquid for the protective layer of Example
1.
Example 7
Preparation of Thermosensitive Recording Material
[0165] The thermosensitive recording material of Example 7 was
prepared in the same manner as Example 1, except that 20 parts of
an aqueous solution of styrene-acrylic acid copolymer resin (acid
value: 100 mgKOH/g, solid content: 10%, Johncryl 450, by Johnson
Polymer Co.) was used in place of the aqueous solution of acrylic
resin for the coating liquid for the protective layer of Example
1.
Example 8
Preparation of Thermosensitive Recording Material
[0166] The thermosensitive recording material of Example 8 was
prepared in the same manner as Example 1, except that 20 parts of
an aqueous solution of styrene-acrylic acid copolymer resin (acid
value: 55 mgKOH/g, solid content: 10%, Johncryl 775, by Johnson
Polymer Co.) was used in place of the aqueous solution of acrylic
resin for the coating liquid for the protective layer of Example
1.
Comparative Example 1
Preparation of Thermosensitive Recording Material
[0167] The thermosensitive recording material of Comparative
Example 1 was prepared in the same manner as Example 1, except that
the aqueous solution of acrylic resin for the coating liquid for
the protective layer of Example 1 was not added.
Comparative Example 2
Preparation of Thermosensitive Recording Material
[0168] The thermosensitive recording material of Comparative
Example 2 was prepared in the same manner as Example 1, except that
an aqueous solution of carboxy-modified polyvinyl alcohol (solid
content: 10%) was used in place of the aqueous solution of
diacetone-modified polyvinyl alcohol (PVA) in the coating liquid
for the protective layer of Example 1, an aqueous solution of
polyamide epichlorohydrin resin (solid content: 10%) was used in
place of the aqueous solution of adipic dihydrazide, and the
aqueous solution of acrylic resin (solid content: 10%) was not
added.
Comparative Example 3
Preparation of Thermosensitive Recording Material
[0169] The thermosensitive recording material of Comparative
Example 3 was prepared in the same manner as Example 1, except that
an aqueous solution of carboxy-modified polyvinyl alcohol (solid
content: 10%) was used in place of the aqueous solution of
diacetone-modified polyvinyl alcohol in the coating liquid for the
protective layer of Example 1, and an aqueous solution of polyamide
epichlorohydrin resin (solid content: 10%) was used in place of the
aqueous solution of adipic dihydrazide.
Comparative Example 4
Preparation of Thermosensitive Recording Material
[0170] The thermosensitive recording material of Comparative
Example 4 was prepared in the same manner as Example 1, except that
an aqueous solution of carboxy-modified polyvinyl alcohol (solid
content: 10%) was used in place of the aqueous solution of
diacetone-modified polyvinyl alcohol in the coating liquid for the
protective layer of Example 1.
[0171] The construction or ingredients of each protective layer of
Examples 1 to 8 and Comparative Examples 1 to 4 are collectively
shown in Table 1.
TABLE-US-00006 TABLE 1 Acid Amount of Value of Acrylic Acrylic PVA
Crosslinking Acrylic Resin (part Resin Resin Agent Resin by mass)
(mgKOH/g) Ex. 1 A-1 C-1 B-1 20 600 Ex. 2 A-1 C-1 B-2 20 195 Ex. 3
A-1 C-1 B-2 2 195 Ex. 4 A-1 C-1 B-2 0.5 195 Ex. 5 A-1 C-1 B-2 45
195 Ex. 6 A-1 C-1 B-2 55 195 Ex. 7 A-1 C-1 B-3 20 100 Ex. 8 A-1 C-1
B-4 20 55 Com. Ex. 1 A-1 C-1 -- -- -- Com. Ex. 2 A-2 C-2 -- -- --
Com. Ex. 3 A-2 C-2 B-1 20 600 Com. Ex. 4 A-2 C-1 B-1 20 600 PVA
Resin A-1: diacetone-modified PVA resin (content of reactive
carbonyl group: 40% by mole) A-2: carboxy-modified PVA resin
Acrylic Resin B-1: sodium polyacrylate, acid value: 600 mgKOH/g,
Jurymer AC103, by Nihon Junyaku Co. B-2: styrene-acryl copolymer,
acid value: 195 mgKOH/g, Johncryl 61J, by Johnson Polymer Co. B-3:
styrene-acryl copolymer, acid value: 100 mgKOH/g, Johncryl 450, by
Johnson Polymer Co. B-4: styrene-acryl copolymer, acid value: 55
mgKOH/g, Johncryl 775, by Johnson Polymer Co. Crosslinking Agent
C-1: adipic dihydrazide C-2: polyamide epichlorohydrin resin
[0172] The thermosensitive recording materials of Examples 1 to 8
and Comparative Examples 1 to 4 were evaluated for their properties
as follows. The results are shown in Table 2.
Evaluation of Water Resistance of Aqueous Flexographic Print
[0173] Each of the thermosensitive recording materials was printed
with an aqueous flexographic ink (diluted into 25% by mass, MTQ
30302-404, by AKZO Nobel Co.) using a wire bar of wire diameter 0.1
mm to form an image, then which was allowed to stand at 22.degree.
C. and 65% RH for 1 hour to dry the image. Then a droplet of water
was dropped on the printed image, and the image was rubbed one time
intensely by a finger after 5 minutes. Water resistance was
evaluated on the basis of the removal level of the printed image in
accordance with the criteria shown below.
Criteria as regards Water Resistance of Aqueous Flexographic
Printing
[0174] A: no removal in printed image
[0175] B: 1% to less than 25% of removal in printed image
[0176] C: 25% to less than 50% of removal in printed image
[0177] D: 50% or more of removal in printed image
Sensitivity Magnification
[0178] Each of the calendered thermosensitive recording materials
was printed at a pulse width of 0.0 to 0.7 msec per 1 msec, using a
thermosensitive printing test apparatus (by Panasonic Electronic
Devices Co.) having a thin-film head, under a condition of head
power of 0.45 W/dot.cndot.line, recording period of 20 msec/L, and
scanning density of 8.times.385 dots/mm, then the print density was
measured using Macbeth densitometer RD914 and the pulse width
corresponding to density 1.0 was calculated.
[0179] The sensitivity magnification was calculated, on the basis
of Comparative Example 1, from the equation of (pulse width in
Comparative Example 1)/(pulse width of measured sample). The larger
is this value, the more proper is the sensitivity of heat
response.
Evaluation of Transportability under High Temperature and High
Humidity Condition
[0180] Each of the calendered thermosensitive recording materials
and a printer (SM-90, by Teraoka Seiko Co.) were allowed to stand
for 1 hour under a high temperature and high humidity condition of
40.degree. C. and 90% RH thereby to control their humidity,
followed by printing and evaluating the transportability based on
the printed length. The print length is the length of a certain
print pattern from the starting point to the ending point of the
pattern printed by the printer. When the transportability is
excellent, the print pattern is correctly printed, thus the length
of the print pattern to be printed and the length of the actually
printed pattern are the same. On the contrary, when the
transportability is inferior, the length of the actually printed
pattern is shorter than the length of the print pattern to be
printed since the printed pattern is shortened by reason of
inferior transportation due to sticking between thermosensitive
recording materials and thermal heads, shortened printing at
printing portions, and also meandering of thermosensitive recording
materials at transportation. A print pattern having a printing
length of 100 mm was used in this test.
Evaluation of Sticking under Low Temperature and Low Humidity
Condition
[0181] Each of the calendered thermosensitive recording materials
and a printer (L'esprit R-12, by Sato Co.) were allowed to stand
for one hour under a low temperature and low humidity condition of
5.degree. C. and 30% RH thereby to control their humidity, followed
by printing and evaluating the sticking property.
[0182] When the sticking property is excellent, the print pattern
is printed correctly. On the contrary, when the sticking property
is inferior, the print pattern cannot be printed correctly since
the pattern is printed in an overlapped condition on the same site
of thermosensitive recording materials. The sticking property was
evaluated in accordance with the following criteria based on visual
inspection for printed images.
Criteria as regards Sticking Property by Visual Inspection
[0183] A: no occurrence of sticking
[0184] B: some sticking occurs, non-problematic on quality
[0185] C: sticking occurs, problematic on quality
[0186] D: incomplete transport, sticking occurs
[0187] E: completely non-transportable
Evaluation of Water Resistance
[0188] The test pieces printed using a print simulator (by Ohkura
Electric Co.) for thermosensitive recording material at energy 1.00
ms were immersed in 100 ml of water at 20.degree. C. for 24 hours,
followed by measuring the image density after the immersion using
Macbeth densitometer RD-914. The higher is the value of the image
density, the more superior is the water resistance.
TABLE-US-00007 TABLE 2 Water Resistance Sensitivity
Transportability Sticking Water of AFP Magnification under HTHH
under LTLH Resistance Ex. 1 B 0.99 100 mm A 1.38 Ex. 2 A 1.00 100
mm A 1.40 Ex. 3 A 1.01 100 mm A 1.39 Ex. 4 B 0.99 100 mm A 1.37 Ex.
5 A 1.00 100 mm A 1.38 Ex. 6 A 1.01 80 mm C 1.39 Ex. 7 A 1.01 100
mm A 1.39 Ex. 8 B 1.00 100 mm A 1.38 Com. Ex. 1 D 1.00 100 mm A
1.38 Com. Ex. 2 A 1.00 50 mm E 1.00 Com. Ex. 3 A 1.00 50 mm E 1.00
Com. Ex. 4 D 1.00 30 mm E 0.50 AFP: Aqueous Flexographic Printing
HTHH: High Temperature and High Humidity Condition LTLH: Low
Temperature and Low Humidity Condition
[0189] The results shown in Table 2 demonstrate that the inventive
thermosensitive recording materials of Examples 1 to 8 exhibit
superior transportability under the high temperature and high
humidity condition, excellent sticking property at low temperature
and low humidity condition, and high water resistance of images
printed by aqueous flexographic ink, while maintaining the higher
sensitivity magnification, compared to the thermosensitive
recording materials of Comparative Examples 1 to 4.
[0190] On the contrary, Comparative Example 1 exhibits poor water
resistance of images printed by aqueous flexographic ink, and the
reason is believed that the protective layer contains a
diacetone-modified polyvinyl alcohol resin (PVA) but no acrylic
resin.
[0191] Comparative Examples 2 and 3 exhibit excellent water
resistance of images printed by aqueous flexographic ink since the
protective layer contains a carboxy-modified PVA, but the sticking
property is poor.
[0192] Comparative Example 4 is inferior in the transportability,
sticking property and water resistance, the reason is believed that
the function of the protective layer is insignificant since the
carboxy-modified PVA and adipic dihydrazide undergo no crosslinking
reaction.
[0193] The thermosensitive recording materials according to the
present invention are free from removal of images printed by
aqueous flexographic ink thereon even after contacting with water
for a long period under conditions or sites where water contacts
with thermosensitive recording material like within refrigerators,
on display racks in supermarkets, or around water systems,
therefore, are appropriate for thermosensitive recording papers,
thermosensitive recording labels, thermosensitive magnetic
recording papers and thermosensitive recording films, and can be
widely used for copy of books and literatures; recording materials
for computers, facsimiles, ticket vendors, label printers,
recorders and handy terminals; display labels for clothes, labels
for parts management, and logistics labels.
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